1. Field of the Invention
This invention relates to improvements in ballasts for fluorescent lamps, more particularly, to a ballast circuit which provides power factor correction of lamp current.
2. Description of the Prior Art
For efficient and proper operation of fluorescent lamps, the ballast for the lamps must be provide power factor correction of lamp current. Thus, lamp current must flow through the entire applied AC sign wave cycle and not only during a portion of this cycle. This requirement is necessary to achieve maximum efficiency of light output from the lamp when considered in view of the power input to the lamp. Also, power factor correction is important from the point of view of a public utility supplying electrical power so as to maintain the most efficient energy transfer from power sub-stations to end users of electrical power.
The techniques for power factor correction which have been known and used in the past for fluorescent lamps have generally been complex in construction and operation. Moreover, such techniques have resulted in circuits which are relatively expensive to produce and maintain. A need has therefore existed for improvements in ballasts for fluorescent lamps so that greater economies can be realized in the operation of fluorescent lamps.